Solution condensation polymerizations of esterified, but unprotected, carbohydrate diacids (aldaric acids) with alkylenediamines to give polyhydroxypolyamides were first reported by Ogata and coworkers1-8 who utilized diesters of acyclic L-tartaric acid1,2 and galactaric (mucic)acid3,4 as diacid monomers. D-glucaric,9-14 meso-xylaric,9,10,15,16 and D-mannaric acid11,14 based polyhydroxypolyamides (PHPAs) were described more recently by others. The primary structural differences between those polymers having alkylendiamine units in common, originate from the variable stereochemistry and number of carbon atoms in the diacid monomer units.
The patent of Kiely and Lin10 describes the preparation of polyhydroxypolyamides from several esterified aldaric acids (carbohydrate diacids) with a number of alkylenediamines, polymerization being carried out without concern for controlling the stereochemical alignment of the diacids, all of which contain chiral carbons. The report of Kiely, Chen and Lin12 describes PHPAs derived only from D-glucaric acid, but with a variety of diamines, including alkylenediamines, diamines with heteroatoms (heterodiamines) in place of one or more carbons in the diamine chain, and arylalkyldiamines. In all of the above preparations of PHPAs, no control of stoichiometry is indicated, and the diacid and diamine monomers are not in an exact 1:1 (molar) stoichiometric relationship in the reaction mixtures. Having a 1:1 molar ratio between reacting monomers is a requirement for forming high molecular weight polymers (17, pp 274-275) by a condensation polymerization process. Consequently, the reported number average molecular weights (Mn) of the PHPAs derived from alkylenediamines as above are typically relatively low and below 3,000. The polyamides have low solubility in methanol, the reported solvent of choice for polymerization, a condition which limits their molecular weights. The report of Morton and Kiely18 describes PHPAs from D-glucaric acid and D-galactaric acid with a number of diamines that also contain a heteroatom or heteroatoms in place of diamine carbon atoms. The resulting polyamides have higher methanol solubility than do those derived from alkylenediamines, which results in significantly higher molecular weights for the PHPAs that precipitate from solution. What these literature sources tell us is: a) that higher molecular weight PHPAs, particularly those with low methanol solubility, are likely to be only achieved by strict control of stoichiometry between the diamine and aldaric acid units, but does not explicitly indicate how this stoichiometry can be achieved in a practical manner; b) enhanced solubilization of the growing polymer is imperative if significantly higher molecular weights are to be achieved.
All patents, patent applications, provisional patent application and publications referred to or cited herein, or from which a claim for benefit of priority has been made, are incorporated by reference in their entirety to the extent they are not inconsistent with the explicit teachings of the specification.